可以使用select、poll或epoll等多路复用机制，避免accept()函数的限制。以下是使用epoll的示例代码：

#include 

// 创建epoll模型
int epollfd = epoll_create(MAX_CLIENTS);

// 监听socket加入epoll监听列表
struct epoll_event ev;
ev.data.fd = listenfd;
ev.events = EPOLLIN | EPOLLET; // 监听读事件，采用ET模式
epoll_ctl(epollfd, EPOLL_CTL_ADD, listenfd, &ev);

while (true) {
    // 监听事件
    struct epoll_event events[MAX_EVENTS];
    int ret = epoll_wait(epollfd, events, MAX_EVENTS, -1);
    if (ret < 0) {
        perror("epoll_wait");
        break;
    }

    for (int i = 0; i < ret; ++i) {
        int fd = events[i].data.fd;
        if (fd == listenfd) { // 监听socket有新连接
            while (true) {
                int connfd = accept(listenfd, (struct sockaddr*)&cliaddr, &clilen);
                if (connfd < 0) { // 没有新连接或发生错误
                    if (errno == EAGAIN || errno == EWOULDBLOCK) { // ET模式，需要sockfd设置为非阻塞
                        break;
                    } else {
                        perror("accept");
                        break;
                    }
                }

                // 新连接加入epoll监听列表
                struct epoll_event ev;
                ev.data.fd = connfd;
                ev.events = EPOLLIN | EPOLLET;
                epoll_ctl(epollfd, EPOLL_CTL_ADD, connfd, &ev);
            }
        } else { // 已连接socket有数据到达
            int nread = 0;
            char buf[MAX_LINE];
            while ((nread = read(fd, buf, MAX_LINE)) > 0) {
                if (write(fd, buf, nread) < 0) {
                    perror("write");
                    return 1;
                }
            }

            if (nread == 0) { // 客户端关闭连接
                epoll_ctl(epollfd, EPOLL_CTL_DEL, fd, NULL);
                close(fd);
            } else if (nread < 0 && errno != EAGAIN && errno != EWOULDBLOCK) {
                perror("read");
                epoll_ctl(epollfd, EPOLL_CTL_DEL, fd, NULL);
                close(fd);
            }
        }
    }